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Analog Devices Inc./Maxim Integrated MAX859ESA+T
- Part No.:
- MAX859ESA+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX859ESA+T.pdf
- Description:
- IC REG BOOST ADJ 125MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,572
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Product details
Overview
The MAX859ESA+T from Maxim Integrated is a high-efficiency, adjustable-output, step-up DC-DC switching regulator optimized for low-input-voltage battery-powered systems. It accepts 0.8V to 6.0V input and delivers 2.7V to 6.0V output with ±1.5% reference tolerance, 125mA peak switch current limit, and 85% efficiency at 100mA - enabling compact, long-life power solutions in glucose meters and portable medical instrumentation.
For engineers reviewing the MAX859ESA+T datasheet, MAX859ESA+T pinout, MAX859ESA+T application, or MAX859ESA+T equivalent, this device requires attention to its adjustable feedback (FB) interface, low-battery detection (LBI/LBO), shutdown control (SHDN), and SO-8 package thermal layout - all critical for ultra-low-quiescent-current (25µA) battery operation in space-constrained designs.
Technical Context
The MAX859ESA+T employs a pulse-frequency modulation (PFM) control scheme with minimum-off-time and constant-peak-current limiting, eliminating the need for an oscillator and enabling variable-frequency switching up to 500kHz. Its internal N-channel sense-FET has ~4Ω on-resistance and starts reliably from 0.8V typical input voltage.
It integrates a precision 1.25V reference (±1.5% over temperature), low-battery comparator with 25mV hysteresis, and open-drain LBO output. The FB pin accepts external resistor dividers to set output voltage, while SHDN enables 1µA shutdown mode - all operating across –40°C to +85°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 0.8V to 6.0V - supports single-cell alkaline, NiMH, or LiFePO₄ batteries down to near-dead voltage. |
| Output Voltage Range | 2.7V to 6.0V - programmable via external resistor divider on FB pin; no fixed-output variants. |
| Peak Switch Current Limit | 125mA ±25mA - constrains inductor size and ripple; enables use of small 22–47µH SMT inductors. |
| Quiescent Supply Current | 25µA - minimizes standby drain in always-on portable devices like glucose meters. |
| Reference Voltage Accuracy | ±1.5% over –40°C to +85°C - ensures stable output regulation across industrial temperature range. |
| Switching Frequency | Up to 500kHz - allows compact LC filter design; frequency varies with load and input voltage. |
| Shutdown Current | 1µA - reduces system-level leakage during sleep modes without external disconnect. |
Pinout & Package
MAX859ESA+T is housed in an 8-pin SO (Small Outline) package with exposed pad not present; JEDEC MS-012AC compliant, 150-mil body width, 1.27mm pitch. Thermal resistance θJA = 170°C/W (SO-8, 2-layer board).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LX | N-channel MOSFET drain | Switch node connecting to external inductor; requires short, low-inductance PCB trace. |
| GND | Power ground | Must connect directly to low-impedance ground plane; shared return for LX, OUT, REF, FB. |
| OUT | Regulator output | Provides bootstrap supply to IC; connects to output capacitor and Schottky rectifier anode. |
| LBI | Low-battery input | Comparator input referenced to 1.25V; connect to voltage divider from VIN for threshold setting. |
| LBO | Low-battery output | Open-drain N-MOS output sinking current when LBI < 1.25V; requires external pull-up to OUT. |
| REF | 1.25V reference output | Stable internal reference; bypass with 0.22µF to GND if loaded; max 250µA source capability. |
| FB | Feedback input | Adjustable-output sensing node; connects to resistor divider between OUT and GND. |
| SHDN | Shutdown control | Active-low logic input; pulls entire circuit into 1µA shutdown state; unclamped, tolerates up to 7V. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low quiescent current | 25µA operating / 1µA shutdown - extends battery life in intermittent-use medical devices. |
| Start-up from 0.8V | Enables operation even as primary cell voltage sags below 1.0V - critical for end-of-life battery support. |
| Integrated low-battery detector | LBI/LBO pair with 25mV hysteresis eliminates need for external supervisor IC in portable systems. |
| Adjustable output via FB pin | Supports precise 2.7–6.0V outputs using standard 1% resistors - avoids inventory of multiple fixed-output SKUs. |
| PFM architecture | Delivers >85% efficiency at light loads without PWM noise; avoids EMI filtering complexity in sensitive analog circuits. |
Applications
| Glucose Meters | Portable Data Collectors |
|---|---|
Use Scenario: Battery-powered handheld device measuring blood glucose concentration with LCD display and microcontroller. IC Role / Device Role / Timing Role: Step-up regulator generating stable 3.3V rail from single 1.5V alkaline cell to power MCU, sensor interface, and display driver. Use Value: 25µA quiescent current preserves battery shelf life; 0.8V start-up ensures full functionality until battery reaches 0.9V. |
Use Scenario: Ruggedized field instrument collecting barcode, RFID, or environmental sensor data on 2-cell NiMH. IC Role / Device Role / Timing Role: Adjustable-output boost converter delivering 5.0V to USB peripherals and 3.3V to MCU core via dual-rail design. Use Value: FB-based adjustability enables one BOM part to support multiple output requirements; SO-8 package simplifies automated assembly. |
| Palmtop Computers | Medical Instrumentation |
Use Scenario: Legacy PDA-style device with monochrome LCD, flash memory, and serial interface powered by two AA cells. IC Role / Device Role / Timing Role: Primary DC-DC converter stepping up 2.4–3.0V battery stack to regulated 5V system bus and 3.3V logic rail. Use Value: 125mA peak switch limit matches typical load profiles; integrated LBO provides early warning before brownout resets. |
Use Scenario: Portable ECG monitor or pulse oximeter requiring low-noise analog front-end and Bluetooth LE radio. IC Role / Device Role / Timing Role: Low-EMI PFM boost regulator powering ADC reference and RF transceiver from coin-cell or button battery. Use Value: Variable-frequency PFM avoids fixed switching harmonics that interfere with analog signal integrity; –40°C to +85°C rating ensures clinical reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-up DC-DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS61200DRCT | Fixed 3.3V/5V outputs only; 1.8V min input; 600mA switch limit; 2.5MHz fixed-frequency PWM. | Higher output current but lacks adjustable output and true sub-1V start-up; unsuitable for deep-discharge battery monitoring. | Select when higher output current and fixed output simplify design; avoid when FB-based adjustment or 0.8V start-up is required. |
| LT1944ES5#TRPBF | Adjustable output; 0.9V min input; 1.2MHz PWM; 400mA switch limit; no integrated LBI/LBO. | Higher switching frequency enables smaller magnetics but adds EMI filtering burden; no built-in battery monitor. | Choose for compact size and higher efficiency above 1V input; add external supervisor if low-battery detection is needed. |
Compared with TPS61200DRCT and LT1944ES5#TRPBF, the MAX859ESA+T uniquely combines sub-1V start-up, integrated LBI/LBO, and FB-adjustable output in a single SO-8 package - making it optimal for ultra-low-power, battery-critical medical and portable instrumentation where runtime and early-warning diagnostics are essential.
Availability
MAX859ESA+T is available at Aetrix Electronics and suitable for glucose meters, portable data collectors, palmtop computers, medical instrumentation, and low-voltage battery-powered equipment requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX859ESA+T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Maxim Integrated (now part of Analog Devices) is a U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, medical, and portable applications.
The MAX856–MAX859 family was designed specifically for ultra-low-power, high-efficiency step-up conversion in battery-constrained systems - emphasizing minimal quiescent current, wide input range, and integrated supervision features.
FAQ
What is the minimum input voltage required for MAX859ESA+T to start switching?
The MAX859ESA+T has a typical start-up supply voltage of 0.8V, meaning it can begin regulation even when the input source (e.g., a nearly depleted alkaline cell) drops to 0.8V. This value is production-tested and guaranteed across the –40°C to +85°C operating range. The actual start-up voltage varies slightly with load and temperature, but remains ≤0.95V under all conditions specified in the datasheet. This capability is intrinsic to the MAX859ESA+T's low-threshold N-channel sense-FET and PFM control architecture.
Can MAX859ESA+T be used with a fixed 3.3V output without external resistors?
No - the MAX859ESA+T is exclusively an adjustable-output variant and does not support fixed 3.3V or 5V operation. Unlike the MAX856/MAX858, it lacks the 3/5 select pin and instead uses the FB pin for feedback. To set 3.3V output, connect a resistor divider (e.g., R1 = 16.9kΩ, R2 = 10kΩ) between OUT and GND, with the junction tied to FB. The MAX859ESA+T's internal 1.25V reference and ±1.5% tolerance ensure accurate regulation when properly configured.
How does the low-battery detection function work on MAX859ESA+T?
The MAX859ESA+T implements low-battery detection via the LBI (input) and LBO (open-drain output) pins. When the voltage at LBI falls below the internal 1.25V reference (with 25mV hysteresis), LBO sinks current to GND. To configure, connect LBI to a resistor divider from VIN; threshold is set by VLBI = 1.25V × (1 + R3/R4). LBO must be pulled up externally (e.g., 10kΩ to OUT) to drive logic inputs. This function is fully integrated - no external comparator or supervisor IC is needed for basic battery monitoring in the MAX859ESA+T.
What is the purpose of the REF pin on MAX859ESA+T, and how should it be bypassed?
REF provides a buffered 1.25V reference output usable for external circuitry such as ADC references or sensor biasing. It sources up to 250µA and sinks up to 20µA while maintaining ±2% accuracy. When driving an external load, bypass REF to GND with a 0.22µF ceramic capacitor. If unloaded, a minimum 0.1µF capacitor suffices. This bypass stabilizes the reference against noise and load transients - a requirement explicitly stated in the MAX859ESA+T datasheet to ensure proper regulation and low-battery comparator accuracy.
Is MAX859ESA+T pin-compatible with other devices in the MAX856–MAX859 family?
No - MAX859ESA+T is not pin-compatible with MAX856/MAX858 (which use the 3/5 pin) or MAX857 (which shares FB but differs in current limit and thermal specs). While all share the same SO-8 footprint, the pin functions differ: MAX859ESA+T uses FB for feedback, whereas MAX856/MAX858 use pin 2 as 3/5 select. Substituting without PCB revision risks misconnection, especially on SHDN, LBO, and FB/LBI routing. Always verify pin mapping per device variant before replacement - MAX859ESA+T requires dedicated layout for its FB-based topology.
MAX859ESA+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Up
- Output Configuration:
- Positive
- Topology:
- Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 0.8V
- Voltage - Input (Max):
- 6V
- Voltage - Output (Min/Fixed):
- 2.7V
- Voltage - Output (Max):
- 6V
- Current - Output:
- 125mA (Switch)
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX859ESA+T FAQ
1.How can I place an order for MAX859ESA+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX859ESA+T on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MAX859ESA+T reliable?
The price and inventory of MAX859ESA+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX859ESA+T is usually 5 days.
3.What payment methods are accepted for MAX859ESA+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX859ESA+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX859ESA+T?
MAX859ESA+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX859ESA+T order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MAX859ESA+T?
For technical support, including MAX859ESA+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX859ESA+T requirements.
6.How does Aetrix verify that MAX859ESA+T is sourced from the original manufacturer or authorized distributors?
All MAX859ESA+T products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MAX859ESA+T meets industry standards.
7.What is the process for return or replacement of MAX859ESA+T?
All MAX859ESA+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX859ESA+T, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MAX859ESA+T part is unused and in its original packaging.
Return procedure for MAX859ESA+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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